Composite of III-nitride crystal on laterally stacked substrates

Abstract

Group-III nitride crystal composites made up of especially processed crystal slices, cut from III-nitride bulk crystal, whose major surfaces are of {1-10±2}, {11-2±2}, {20-2±1} or {22-4±1} orientation, disposed adjoining each other sideways with the major-surface side of each slice facing up, and III-nitride crystal epitaxially present on the major surfaces of the adjoining slices, with the III-nitride crystal containing, as principal impurities, either silicon atoms or oxygen atoms. With x-ray diffraction FWHMs being measured along an axis defined by a <0001> direction of the substrate projected onto either of the major surfaces, FWHM peak regions are present at intervals of 3 to 5 mm width. Also, with threading dislocation density being measured along a <0001> direction of the III-nitride crystal substrate, threading-dislocation-density peak regions are present at the 3 to 5 mm intervals.

What is claimed is: 
     
       1. A Group-III nitride crystal substrate having, on opposite sides of the substrate, major surfaces of plane orientation other than {0001}, the III-nitride crystal substrate characterized:
 by a property that with x-ray diffraction full-width-at-half-maximums (FWHMs) being measured along an axis defined by a <0001> direction of the substrate projected onto either of the major surfaces, FWHM peak regions are present at inter-peak-region intervals of 3 to 5 mm width; and 
 in being of plane orientation selected from the group consisting of {1-100}, {11-20}, {1-10±2}, {11-2±2}, {20-2±1} and {22-4±1}. 
 
     
     
       2. The III-nitride crystal substrate of  claim 1 , further characterized by a property that with threading dislocation density being measured along a <0001> direction of the III-nitride crystal substrate, threading-dislocation-density peak regions are present at inter-peak-region intervals of 3 to 5 mm width. 
     
     
       3. The III-nitride crystal substrate of  claim 1 , further characterized by containing, as principal impurities, either oxygen atoms or silicon atoms. 
     
     
       4. The III-nitride crystal substrate of  claim 1 , further characterized by a property of having x-ray diffraction peaks whose tips are divided.